init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Bcpg/OpenPgp/SXprUtilities.cs

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+using System.IO;
+using Org.BouncyCastle.Utilities.IO;
+
+namespace Org.BouncyCastle.Bcpg.OpenPgp;
+
+public sealed class SXprUtilities
+{
+	private class MyS2k : S2k
+	{
+		private readonly long mIterationCount64;
+
+		public override long IterationCount => mIterationCount64;
+
+		internal MyS2k(HashAlgorithmTag algorithm, byte[] iv, long iterationCount64)
+			: base(algorithm, iv, (int)iterationCount64)
+		{
+			mIterationCount64 = iterationCount64;
+		}
+	}
+
+	private SXprUtilities()
+	{
+	}
+
+	private static int ReadLength(Stream input, int ch)
+	{
+		int num = ch - 48;
+		while ((ch = input.ReadByte()) >= 0 && ch != 58)
+		{
+			num = num * 10 + ch - 48;
+		}
+		return num;
+	}
+
+	internal static string ReadString(Stream input, int ch)
+	{
+		int num = ReadLength(input, ch);
+		char[] array = new char[num];
+		for (int i = 0; i != array.Length; i++)
+		{
+			array[i] = (char)input.ReadByte();
+		}
+		return new string(array);
+	}
+
+	internal static byte[] ReadBytes(Stream input, int ch)
+	{
+		int num = ReadLength(input, ch);
+		byte[] array = new byte[num];
+		Streams.ReadFully(input, array);
+		return array;
+	}
+
+	internal static S2k ParseS2k(Stream input)
+	{
+		SkipOpenParenthesis(input);
+		ReadString(input, input.ReadByte());
+		byte[] iv = ReadBytes(input, input.ReadByte());
+		long iterationCount = long.Parse(ReadString(input, input.ReadByte()));
+		SkipCloseParenthesis(input);
+		return new MyS2k(HashAlgorithmTag.Sha1, iv, iterationCount);
+	}
+
+	internal static void SkipOpenParenthesis(Stream input)
+	{
+		int num = input.ReadByte();
+		if (num != 40)
+		{
+			throw new IOException("unknown character encountered");
+		}
+	}
+
+	internal static void SkipCloseParenthesis(Stream input)
+	{
+		int num = input.ReadByte();
+		if (num != 41)
+		{
+			throw new IOException("unknown character encountered");
+		}
+	}
+}